{"id":"CVE-2026-64581","state":"PUBLISHED","title":"xfrm: fix sk_dst_cache double-free in xfrm_user_policy()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nxfrm: fix sk_dst_cache double-free in xfrm_user_policy()\n\nxfrm_user_policy() clears the socket dst cache with __sk_dst_reset(),\ni.e. the non-atomic __sk_dst_set(sk, NULL): it reads sk_dst_cache with\nrcu_dereference_protected(), stores NULL and dst_release()s the old dst.\nThat is only safe if no other thread modifies sk_dst_cache concurrently.\n\nFor a connected UDP socket that does not hold: the transmit fast path\n(udp_sendmsg -> sk_dst_check -> sk_dst_reset) resets the cache locklessly\nwith an atomic xchg(). A per-socket policy change racing a send can make\nboth sides observe the same old dst and each dst_release() it, dropping\nthe socket's single reference twice and freeing the xfrm_dst bundle while\nit is still referenced:\n\n  BUG: KASAN: slab-use-after-free in dst_release\n  Write of size 4 at addr ffff88801897b6c0 by task exploit/155\n  Call Trace:\n   ...\n   dst_release (... ./include/linux/rcuref.h:109)\n   xfrm_user_policy (./include/net/sock.h:2239 ./include/net/sock.h:2256 net/xfrm/xfrm_state.c:3053)\n   do_ip_setsockopt (net/ipv4/ip_sockglue.c:1347)\n   ip_setsockopt (net/ipv4/ip_sockglue.c:1417)\n   do_sock_setsockopt (net/socket.c:2368)\n   __sys_setsockopt (net/socket.c:2393)\n   __x64_sys_setsockopt (net/socket.c:2396)\n   do_syscall_64 (arch/x86/entry/syscall_64.c:94)\n   entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)\n\nReachable by an unprivileged user via a user+network namespace.\n\nUse the atomic sk_dst_reset() so the cache is cleared and released with a\nsingle xchg(): whichever side wins releases the dst once, the other sees\nNULL and does nothing. Behaviour is otherwise unchanged.","publishedAt":"2026-08-05T08:09:35.556Z","updatedAt":"2026-10-19T20:48:43.050Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"2b06cdf3e688b98fcc9945873b5d42792bd4eee0","status":"affected","lessThan":"e8686fd8d18b99f3a9038683045b2f2338a7706d","versionType":"git"},{"version":"2b06cdf3e688b98fcc9945873b5d42792bd4eee0","status":"affected","lessThan":"a9340ebdc13f8bb5063c0bc0b037ee7e640d4ae9","versionType":"git"},{"version":"2b06cdf3e688b98fcc9945873b5d42792bd4eee0","status":"affected","lessThan":"f833821e4b52ab6335d443ede5fb79c38e61d19a","versionType":"git"},{"version":"2b06cdf3e688b98fcc9945873b5d42792bd4eee0","status":"affected","lessThan":"f0ab9a71167bae308e05ab13b65e2007504a603f","versionType":"git"},{"version":"2b06cdf3e688b98fcc9945873b5d42792bd4eee0","status":"affected","lessThan":"8dd8929b71c4f06c614f8f54c2cc070453faae16","versionType":"git"},{"version":"2b06cdf3e688b98fcc9945873b5d42792bd4eee0","status":"affected","lessThan":"0ea8f06454012d9e7f9c6e6253df710949bf6294","versionType":"git"},{"version":"2b06cdf3e688b98fcc9945873b5d42792bd4eee0","status":"affected","lessThan":"96b678d08268b5f5c6fc99d4289d9b7e334fc683","versionType":"git"},{"version":"2b06cdf3e688b98fcc9945873b5d42792bd4eee0","status":"affected","lessThan":"c283e9ada7fcb7dd4b10592623086b2e6d2f9925","versionType":"git"},{"version":"72f157be2f81910ae759bfe2e5c2256fc4625645","status":"affected","versionType":"git"},{"version":"9e9fe58a92a46c6d154d2901735bf230d91b8507","status":"affected","versionType":"git"},{"version":"adc1ec6cdc20d430aa01b86497220709b9149466","status":"affected","versionType":"git"},{"version":"b54033eb1cfd77aba471269ddd804ed8d3e35dea","status":"affected","versionType":"git"},{"version":"c9e82cb34c3c2ee895af01bc899c6ed0bc6eb04a","status":"affected","versionType":"git"},{"version":"5eef9b51114fcc65651d671add52f267f91b9451","status":"affected","versionType":"git"},{"version":"3.16.52","status":"affected","lessThan":"3.17","versionType":"semver"},{"version":"4.4.163","status":"affected","lessThan":"4.5","versionType":"semver"},{"version":"3.18.101","status":"affected","lessThan":"3.19","versionType":"semver"},{"version":"4.1.52","status":"affected","lessThan":"4.2","versionType":"semver"},{"version":"4.4.123","status":"affected","lessThan":"4.5","versionType":"semver"},{"version":"4.9.89","status":"affected","lessThan":"4.10","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/xfrm/xfrm_state.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.14","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.14","versionType":"semver"},{"version":"5.10.267","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.218","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.185","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.154","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.106","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.47","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.6","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/xfrm/xfrm_state.c"]}],"references":["https://git.kernel.org/stable/c/e8686fd8d18b99f3a9038683045b2f2338a7706d","https://git.kernel.org/stable/c/a9340ebdc13f8bb5063c0bc0b037ee7e640d4ae9","https://git.kernel.org/stable/c/f833821e4b52ab6335d443ede5fb79c38e61d19a","https://git.kernel.org/stable/c/f0ab9a71167bae308e05ab13b65e2007504a603f","https://git.kernel.org/stable/c/8dd8929b71c4f06c614f8f54c2cc070453faae16","https://git.kernel.org/stable/c/0ea8f06454012d9e7f9c6e6253df710949bf6294","https://git.kernel.org/stable/c/96b678d08268b5f5c6fc99d4289d9b7e334fc683","https://git.kernel.org/stable/c/c283e9ada7fcb7dd4b10592623086b2e6d2f9925"],"weaknesses":["CWE-362"],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/64xxx/CVE-2026-64581.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-64581","state":"PUBLISHED","datePublished":"2026-08-05T08:09:35.556Z","dateUpdated":"2026-10-19T20:48:43.050Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T15:36:31.798Z"},"containers":{"cna":{"title":"xfrm: fix sk_dst_cache double-free in xfrm_user_policy()","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nxfrm: fix sk_dst_cache double-free in xfrm_user_policy()\n\nxfrm_user_policy() clears the socket dst cache with __sk_dst_reset(),\ni.e. the non-atomic __sk_dst_set(sk, NULL): it reads sk_dst_cache with\nrcu_dereference_protected(), stores NULL and dst_release()s the old dst.\nThat is only safe if no other thread modifies sk_dst_cache concurrently.\n\nFor a connected UDP socket that does not hold: the transmit fast path\n(udp_sendmsg -> sk_dst_check -> sk_dst_reset) resets the cache locklessly\nwith an atomic xchg(). A per-socket policy change racing a send can make\nboth sides observe the same old dst and each dst_release() it, dropping\nthe socket's single reference twice and freeing the xfrm_dst bundle while\nit is still referenced:\n\n  BUG: KASAN: slab-use-after-free in dst_release\n  Write of size 4 at addr ffff88801897b6c0 by task exploit/155\n  Call Trace:\n   ...\n   dst_release (... ./include/linux/rcuref.h:109)\n   xfrm_user_policy (./include/net/sock.h:2239 ./include/net/sock.h:2256 net/xfrm/xfrm_state.c:3053)\n   do_ip_setsockopt (net/ipv4/ip_sockglue.c:1347)\n   ip_setsockopt (net/ipv4/ip_sockglue.c:1417)\n   do_sock_setsockopt (net/socket.c:2368)\n   __sys_setsockopt (net/socket.c:2393)\n   __x64_sys_setsockopt (net/socket.c:2396)\n   do_syscall_64 (arch/x86/entry/syscall_64.c:94)\n   entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)\n\nReachable by an unprivileged user via a user+network namespace.\n\nUse the atomic sk_dst_reset() so the cache is cleared and released with a\nsingle xchg(): whichever side wins releases the dst once, the other sees\nNULL and does nothing. Behaviour is otherwise unchanged."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"2b06cdf3e688b98fcc9945873b5d42792bd4eee0","status":"affected","lessThan":"e8686fd8d18b99f3a9038683045b2f2338a7706d","versionType":"git"},{"version":"2b06cdf3e688b98fcc9945873b5d42792bd4eee0","status":"affected","lessThan":"a9340ebdc13f8bb5063c0bc0b037ee7e640d4ae9","versionType":"git"},{"version":"2b06cdf3e688b98fcc9945873b5d42792bd4eee0","status":"affected","lessThan":"f833821e4b52ab6335d443ede5fb79c38e61d19a","versionType":"git"},{"version":"2b06cdf3e688b98fcc9945873b5d42792bd4eee0","status":"affected","lessThan":"f0ab9a71167bae308e05ab13b65e2007504a603f","versionType":"git"},{"version":"2b06cdf3e688b98fcc9945873b5d42792bd4eee0","status":"affected","lessThan":"8dd8929b71c4f06c614f8f54c2cc070453faae16","versionType":"git"},{"version":"2b06cdf3e688b98fcc9945873b5d42792bd4eee0","status":"affected","lessThan":"0ea8f06454012d9e7f9c6e6253df710949bf6294","versionType":"git"},{"version":"2b06cdf3e688b98fcc9945873b5d42792bd4eee0","status":"affected","lessThan":"96b678d08268b5f5c6fc99d4289d9b7e334fc683","versionType":"git"},{"version":"2b06cdf3e688b98fcc9945873b5d42792bd4eee0","status":"affected","lessThan":"c283e9ada7fcb7dd4b10592623086b2e6d2f9925","versionType":"git"},{"version":"72f157be2f81910ae759bfe2e5c2256fc4625645","status":"affected","versionType":"git"},{"version":"9e9fe58a92a46c6d154d2901735bf230d91b8507","status":"affected","versionType":"git"},{"version":"adc1ec6cdc20d430aa01b86497220709b9149466","status":"affected","versionType":"git"},{"version":"b54033eb1cfd77aba471269ddd804ed8d3e35dea","status":"affected","versionType":"git"},{"version":"c9e82cb34c3c2ee895af01bc899c6ed0bc6eb04a","status":"affected","versionType":"git"},{"version":"5eef9b51114fcc65651d671add52f267f91b9451","status":"affected","versionType":"git"},{"version":"3.16.52","status":"affected","lessThan":"3.17","versionType":"semver"},{"version":"4.4.163","status":"affected","lessThan":"4.5","versionType":"semver"},{"version":"3.18.101","status":"affected","lessThan":"3.19","versionType":"semver"},{"version":"4.1.52","status":"affected","lessThan":"4.2","versionType":"semver"},{"version":"4.4.123","status":"affected","lessThan":"4.5","versionType":"semver"},{"version":"4.9.89","status":"affected","lessThan":"4.10","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/xfrm/xfrm_state.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.14","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.14","versionType":"semver"},{"version":"5.10.267","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.218","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.185","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.154","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.106","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.47","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.6","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/xfrm/xfrm_state.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/e8686fd8d18b99f3a9038683045b2f2338a7706d"},{"url":"https://git.kernel.org/stable/c/a9340ebdc13f8bb5063c0bc0b037ee7e640d4ae9"},{"url":"https://git.kernel.org/stable/c/f833821e4b52ab6335d443ede5fb79c38e61d19a"},{"url":"https://git.kernel.org/stable/c/f0ab9a71167bae308e05ab13b65e2007504a603f"},{"url":"https://git.kernel.org/stable/c/8dd8929b71c4f06c614f8f54c2cc070453faae16"},{"url":"https://git.kernel.org/stable/c/0ea8f06454012d9e7f9c6e6253df710949bf6294"},{"url":"https://git.kernel.org/stable/c/96b678d08268b5f5c6fc99d4289d9b7e334fc683"},{"url":"https://git.kernel.org/stable/c/c283e9ada7fcb7dd4b10592623086b2e6d2f9925"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - Triggered via setsockopt(IP_XFRM_POLICY/IP_IPSEC_POLICY) on a local socket racing concurrent udp_sendmsg; entry is a local syscall path (do_ip_setsockopt -> xfrm_user_policy), not packet processing.\nAC:L - Attacker controls both sides of the race (one thread setsockopt to clear/apply per-socket xfrm policy, another sendmsg on the same connected UDP socket) and can create the obsolete xfrm_dst precondition in their netns, retrying until the double dst_release wins.\nPR:L - Path requires CAP_NET_ADMIN checked with sockopt_ns_capable(sock_net(sk)->user_ns), which an unprivileged user obtains via user+network namespaces; the fix commit explicitly states this reachability.\nUI:N - Exploitation uses only the attacker's own socket, threads, and setsockopt/sendmsg loops; no victim action or cooperation is required.\nS:U - Double-free/UAF of the socket's dst_entry/xfrm_dst is standard local kernel memory corruption within the host kernel authority, not a VM escape or other cross-boundary impact.\nC:H - Double dst_release frees the xfrm_dst slab object while still referenced, yielding a use-after-free that can be reclaimed/sprayed to disclose kernel memory via corrupted dst contents and ops.\nI:H - The UAF targets a dst_entry with function pointers (ops/input/output) used on transmit, enabling heap reuse for arbitrary write and control-flow hijack consistent with comparable sk_dst_cache races.\nA:H - The KASAN slab-use-after-free in dst_release demonstrates kernel memory corruption that can oops/panic, and the attacker can repeat the race freely."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-27T12:39:44.254Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14","versionEndExcluding":"5.10.267"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14","versionEndExcluding":"5.15.218"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14","versionEndExcluding":"6.1.185"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14","versionEndExcluding":"6.6.154"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14","versionEndExcluding":"6.12.106"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14","versionEndExcluding":"6.18.47"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14","versionEndExcluding":"7.1.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14","versionEndExcluding":"7.2"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.16.52"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.4.163"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.18.101"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.1.52"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.4.123"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9.89"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-64581","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T15:43:16.753183Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-362","lang":"en","type":"CWE","description":"CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-19T20:48:43.050Z"}}]}}}